From acae97e70fe0c6c3354960e2e89a1157d06cfdaa Mon Sep 17 00:00:00 2001
From: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
Date: Thu, 27 Jul 2023 11:53:46 +0800
Subject: [PATCH] os/mac/mach: resolve rpaths too
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We can add a small amount of logic to `#resolve_variable_name` that will
allow us to perform (limited) resolution of rpath references. This is
for informational purposes only: failing to resolve an `@rpath`
reference will not (and should not) result in `brew linkage` failures.

`dyld` will typically have more information than we do to resolve these
references, so not failing `brew linkage` when we fail to resolve an
`@rpath` reference is the right behaviour here.

As an example, before:

    ❯ brew linkage jpeg-turbo
    System libraries:
      /usr/lib/libSystem.B.dylib
    @rpath-referenced libraries:
      @rpath/libjpeg.8.dylib
      @rpath/libturbojpeg.0.dylib

After:

    ❯ brew linkage jpeg-turbo
    System libraries:
      /usr/lib/libSystem.B.dylib
    Homebrew libraries:
      /usr/local/Cellar/jpeg-turbo/3.0.0/lib/libjpeg.8.dylib (jpeg-turbo)
      /usr/local/Cellar/jpeg-turbo/3.0.0/lib/libturbojpeg.0.dylib (jpeg-turbo)
---
 Library/Homebrew/os/mac/mach.rb | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Library/Homebrew/os/mac/mach.rb b/Library/Homebrew/os/mac/mach.rb
index f9818d6f84..38f52dc4c9 100644
--- a/Library/Homebrew/os/mac/mach.rb
+++ b/Library/Homebrew/os/mac/mach.rb
@@ -110,11 +110,22 @@ module MachOShim
       Pathname(name.sub("@loader_path", dirname)).cleanpath.to_s
     elsif name.start_with?("@executable_path") && binary_executable?
       Pathname(name.sub("@executable_path", dirname)).cleanpath.to_s
+    elsif name.start_with?("@rpath") && (target = resolve_rpath(name)).present?
+      target
     else
       name
     end
   end
 
+  def resolve_rpath(name)
+    target = T.let(nil, T.nilable(String))
+    return unless rpaths(resolve_variable_references: true).find do |rpath|
+      File.exist?(target = File.join(rpath, name.delete_prefix("@rpath")))
+    end
+
+    target
+  end
+
   def archs
     mach_data.map { |m| m.fetch :arch }
   end